Chisel and piston retainer



Aug. 14, 1928.

E. H. SHAFF CHISEL AND PISTON RETAINER Filed Oct. l, 1924 kaf f,

Patented Aug. .14, 192s.

UNITED STATES PATENT OFFlC-E.

ERNEST H. SHAFF, 0F GRAND HAVEN, MICHIGAN, ASSIGNORTO WM. H. KELLER, INC., 0F GRAND HAVEN, MICHIGAN, A CORPORATION 0F MICHIGAN.

CHISEL AND PISTON RETAINER.

Application led October 1,1924. Serial No. 741,099.

The invention relates to percussion tools such as rivet cutters wherein the impact imparted by the piston to the working tool must be relatively great, and it has for its general aim the provision of a retaining device, for the working tool and also for the piston.

The primaryobject of the invention is to provide a retaining device embodying a yielding means for retaining the chisel or other working tool in operative position in` the tool proper, in combination with a means for cushioning the tool pistonL at the end of its forward stroke after havin imparted to the working tool the impact -w ich is to perform the desired operation.

A General object of the invention is to provide a retaining means of athoroughly practical character, simple in construction, readily and conveniently manipulable and not likely to become disassembled in use.

In the accompanying drawings I have shown a preferred embodiemnt of my invention. It is contemplated, however, that various changes may be made in the construction set forth without departing from the spirit and scope of my invention as expressed in the appended claims.

Figure 1 of the drawings is a side elevational view illustrating my improved retaining means as applied to a percussion tool, the retainer being partially broken away to show a detail of construction.

Fig. 2- is a horizontal section through the forward end of the tool and the portion of the retainer which is secured thereto, the remaining ortion of the retainer and the cutting tool` ing shown in top plan view.

Fig. 3 is an end view looking from the left of Fig.' 1. v

Fig. 4 is a transverse sectional view taken in the plane of line 4 4 of Fig. 2. 4

The retaining means of m invention comprises a cylindrical member screwthreaded upon the forward end of the tool body indicated at 8. Within the portion of the mem- `ber 7, projecting forwardly from the 4tool cylinder 8, isa cylindrical cushioning element 9 referably of rubber. 'I'he forward end of this element bears against an inturned flange 10 at the forward end of the cylmdrical member 7 Said flan e denes a central lopening 11 through whic passes the shank 12 of. a working tool or chisel 13, the shank also passing through the cylindrical cushlon lemsent 9 into the forward end-of the cylin- The opposite end of the cushion element 9 bears against the forward face of an out turned flange 14 of a bushing 15 entered in the forward end of the cylinder, with the rear face of said-llange abuttin the forward end of the cylinder. The bus ing 15 slidably receivesa reduced rear end portion 16 of the chisel, andsuch reduced portion projects rearwardly beyond the end of the bushing 15 to receive the'impact of the tool iston 17. vThe arrangement is such that a ter action, my retaining device is also adapted to l vyieldably restrain the discharge 0f the cutting tool or chisel 13. To this end it comprises a substantially U-shaped member 18 mounted forwardly of the tool proper upon a pair of arms 19 having their rear ends supported in the member 7 The member 18 is adapted to straddle the forward end of the tool or chisel so thatv the latter is free to slide relative thereto, and interposed between said member 18 and a-collar 20 formed on the tool at the forward end of the shank portion 12 is a coiled'compression s ring 21 which yields under the impact o the piston 17 against the tool shank and thus restrains the chisel fromdischarge.

The mounting of the arms 19 in the member 7 is such as to permit theyokeA 18 to be swung laterally out of alinement with the forward end of the spring 21 and .thuspermit of,the removal lof the cutting tool without disassembling the retainer. This mounting consists in the present instance and by reference of inturned trunnions'22 formed integral with the arms 19 and engaging 1n diametrically opposite holes 23 inthe forward end of the member 7. The arrangement is suchv that the arms 19tend to spring inwardly or in a direction toward each other, andthe inner surfaces' of the arms lie 1n longitudinally extending grooves 24 in opposite sides of the member 7 The arms thus tend to remain in a straight ahead position because of their tendency to move inwardly with a spring action. To insure that the member 18 shall not swing upwardly when the tool is in operation, I provide rearwardly extending lugs 25 on the rear face of thc member 18 which engage with the under side of the foremost coil of the spring 21.

To facilitate the insertion of the inturned trunnions 22 in the holes 23, I provide angular grooves 26 in the outer periphery of the member 7 at diametrically opposite sides thereof, the inner ends of the grooves terminating in the holes 23 and the 'outer ends thereof being flush with the forward end of the member 7. Moreover, the forward ends of the grooves may have the bottoms beveled as at 27. It will be apparent that the trungrooves 26 and then twisted laterally or circumferentially of the member 7 until they snap into the holes 23 with the arms 19 lying in the grooves 24. The latter thus serve to hold the trunnions in their holes 23.

In Figure l I have shown in broken lines the member 18 swung upwardly 1nto a posltion such asto permit the removal of the tool 13. In such movement the arms 19 ride out" of the grooves 24; which lattte'r, it will be seen from Fig. 4, have rounded bottoms conforming substantially to the curvatureofthe arms.

The member 7 may, if desired, be locked upon the tool cylinder 8 by means of a bolt 28 serving to connect -the. opposed portions of the rear end of the member 7 formed by a slot 29 in one wall thereof.

The operation of the device will be readily understood from the foregoing description. It will be apparent that the invention is especially applicable to tools used for such purposes as cutting rivets and the like where the blow delivered to the cutting tool is very great. Heretofore in such tools it has been customary simply Ato retain the chisel, some cushioning means being usually provided, the piston, afterv delivering itsimpact against the tool mons may be readily slid rearwardly in the being in some instances cushionedl by the compression ofthe air in the forward end ofthe cylinder. I believe that I am the first to have produced a retainer performing the dual function of retaining the chisel with a cushioning action and retaining the chisel in a manner such as to absorb the shock of the piston against the forward end of the tool cylinder after delivering its blow.

claim as my invention:

1. A retainer of the character described con'iprising in combination with a tool cylinder and a working tool, a supporting member screw-threaded upon the exterior of the cylinder, a bushing within the cylinder interposed between the forward end of the cylinder and the shank of the working tool, said shank having a shoulder adapted to engage the forward end of said bushing to limit the rearward movement of the cutting tool7 and means located forwardly of said supporting member adapted yieldably to limit the forward movement of the cutting tool, said means acting to hold the cutting tool normally seated against said bushing.

2. A retainer of the character described comprising in combination with a tool cylinder and a working tool, a` supportingr member screw-threaded upon the exterior of the cylinder, a bushing arranged to slide in the forward end'of the cylinder about the shank of the working tool, said shank having a shoulder adapted to engage the forward end of said bushing to limit the rearward movement of the working tool, means located forwardly of said supporting member adapted yieldably to limit the forward movement of the working tool, said means acting to hold the cutting tool normally seated against said bushing,Y and a sleeve of yieldable material interposed between said supporting member and said bushing adapted yieldably to restrain the discharge of the piston from the tool cylinder.

4-In testimony whereof, I have hereunto affixed my signature.

ERNEST H. SHAFF. 

